How the Turn Signal Switch Works

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Steve Nau
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How the Turn Signal Switch Works

#1 Post by Steve Nau »

356TurnSignalSwitch.pdf
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After spending the last few days working on my turn signal switch I thought I had it figured out.
So I decided to try to document how the switch wiring works.

Attached is my diagram but something doesn't seem right so hopefully someone smarter than me can tell me where I went wrong.
I numbered the six wires along with their colors. The numbers are based on the wiring loom tags on my harness.
I numbered the contacts on the switch circuit board and then tried to document what contacts and wires are connected when the switch is activated.
As you will see it looks like I have something wrong as it relates to the front signal lights.

Corrections please.
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Steve Nau
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Re: How the Turn Signal Switch Works

#2 Post by Steve Nau »

Correction # 1 - I had a wire labeled wrong
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Brad Ripley
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Re: How the Turn Signal Switch Works

#3 Post by Brad Ripley »

What model are your working on? You will find complete diagrams in Joe Leoni's books. See http://www.stoddard.com/catalogsearch/result/?q=WKD-356

or you can order https://porsche356registry.org/classifieds/19536

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Greg Bryan
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Re: How the Turn Signal Switch Works

#4 Post by Greg Bryan »

Steve - coincidentally, I was working on a wiring diagram for the 550 cars and the original Porsche 550 pencil drawing I'm working from has a very good depiction of the turn signal inner workings, which I have duplicated. In the attached diagram, you will see two 'W' shaped contacts. These are attached to the turn signal stalk and rotate through about 30* when right or left turn signal is selected, as shown in the diagram on the right. The Ws are brass contacts and the crescent shapes and dots are also brass contacts .
The diagram with the wires shows the switch in the neutral position - the brake light wire from the B/L switch is in contact with the bottom W and the two crescents providing a power path to the combined Brake Light/Rear Turn Signal bulbs. In the neutral position, only Brake Lights are enabled. You'll notice that the upper W is not in contact with any other wire except the input from the flasher.
When the driver selects a turn signal direction - Left in this example - contact is made on the upper W between the #54 wire (Black/Green/White) and the front and rear left turn signal circuits.
Right Brake Light is also still enabled, but Left Brake is not since it's flashing for the turn signal function
The turn signal switch pretty much works this way for all model 356s
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T2 Turn Signal Switch.png
Greg Bryan

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Steve Nau
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Re: How the Turn Signal Switch Works

#5 Post by Steve Nau »

Thanks. That seems to match pretty well with what I have and fills in a few blanks for me.

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